1. Field of the Invention
This invention relates to pharmaceutical compositions comprising bimatoprost.
2. Description of Related Art
Bimatoprost, shown below, is a prostamide marketed commercially for the treatment of glaucoma and ocular hypertension.

Benzalkonium chloride (BAK) is a preservative used in many commercial ophthalmic products to prevent microbial contamination in multi-use products. The commercial eye drops (Bimatoprost, Allergan, Inc., Irvine, Calif.) contain 0.03% bimatoprost and 0.005% BAK. Although no other prostamides are currently marketed for the treatment of glaucoma, several prostaglandin analogs are commercially available which use BAK as a preservative. These include latanoprost (Xalatan), travoprost (Travatan), and unoprostone isopropyl (Rescula), which require significantly more BAK, from 150-200 ppm, to meet antimicrobial effectiveness tests in the United States and Europe.
U.S. Pat. No. 6,596,765 B2 discloses a composition comprising 0.005% or 0.0005% latanoprost and 0.2 mg/mL BAK.
U.S. Pat. No. 6,646,001 B2 discloses compositions comprising 0.03% bimatoprost and 0.01% BAK or “0.01%+5% excess” BAK.